Vapour recovery unit for steam assisted gravity drainage (SAGD) system

Abstract

A vapour recovery process for a SAGD (Steam Assisted Gravity Drainage) system for a heavy oil recovery facility, the process comprising a venturi ejector having one active inlet, one passive inlet and one outlet, the active inlet being supplied with natural gas to provide gas flow sufficient to operate the ejector, the passive inlet being connected to a mixture of vented vapours from storage tanks and low pressure equipment, and the outlet supplying fuel to a system along with the natural gas; wherein the movement of the natural gas through the ejector creates a vacuum so as to draw the vapours from the tanks and low pressure equipment into the ejector and then toward the low pressure fuel system, wherein the vented vapours are burned, instead of being released to the atmosphere.

Description

FIELD OF THE INVENTION[0001]This invention pertains to the field of jet technology, specifically for the evacuation of low pressure gases and diversion into a fuel system instead of release to the atmosphere.BACKGROUND OF THE INVENTION[0002]Ejectors, jet pumps and eductors have been used for many years in different applications as a means of pumping, vacuuming and mixing. The ejectors operate on the principle of a venturi, through which an energized fluid is directed causing a differential pressure across an orifice situated in a mixing chamber. The mixing chamber has a port to allow gases at a lower pressure than the energizing fluid pressure to be drawn into the chamber due to the created differential between the energized / pressurized line and the lower pressure inlet line. The mixed fluids depart from the chamber at a reduced pressure less than the inlet energized fluid but greater than the lower pressure fluid drawn into the mixing chamber.[0003]Systems utilizing ejectors are no...

AI Technical Summary

Benefits of technology

The vapor recovery unit (VRU) system described in this patent is designed to collect low pressure gases and compress them for use in a fuel gas system. The system prevents the release of toxic or flammable gases to the atmosphere. The invention also includes emergency overpressure protection to reduce the required capacity of the system. The tanks are kept under positive pressure to further minimize the potential for air ingress. The new ejector design takes advantage of the large pressure drop to efficiently transfer the recovered gases to the fuel gas system.

Problems solved by technology

Systems utilizing ejectors are not new in the art.

Further, closed systems require additional equipment to deal with the safety of the system.

Since the tanks can contain toxic or flammable gases, discharging the gases to atmosphere on a normal basis is not acceptable.

These systems are expensive, vulnerable to malfunctions and require regular maintenance.

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